Field
The present inventive concept relates to a method of learning a touch point of a clutch, and more particularly, to a method of learning a touch point of a clutch, in which a touch point learning mode is entered based on judgment about the state of clutches and a touch point is determined based on the rotational speeds of a drive shaft clutch, a non-drive shaft clutch and an engine.
Description of the Related Art
A dual-clutch transmission (DCT) is an automatic transmission including two clutches. It is a clutch system that selectively transmits torque received from an engine to two input shafts using two clutches. Since gears are disposed on the two input shafts, power corresponding to a gear ratio is transmitted to wheels.
Here, each of the clutches transmits the torque of the engine to the wheels by switching, stage by stage, from a clutch open state in which the clutch is physically separated from the engine to a slip state in which the clutch begins to have friction and thus a difference in speed between both ends of the clutch becomes equal to or greater than a predetermined value and then to a lockup state in which there is no difference in speed between both ends of the clutch and the torque of the engine transmitted to the input shaft of the clutch is transmitted to an output shaft connected to the wheels. When the clutch is separated from the engine, the above process is performed in the reverse order.
A touch point is a position at which a clutch slips, that is, a position at which the clutch begins to receive power from an engine. The touch point may vary according to temperature change or abrasion. Therefore, for stable operation of the clutch, it is important to learn the position of the touch point in advance.
Accordingly, there is a need for a new form of touch point learning method which makes it possible to reduce a clutch control error by accurately learning a touch point.